Proximity monitor related fixes. (#51544)

* Makes cameras create prox monitors only when necessary.

* typofix

* Makes proximity monitors behave properly on shuttle moves.

* Makes transit turfs work without crosslinked levels.

code/modules/shuttle/on_move.dm

@@ -121,6 +121,8 @@ All ShuttleMove procs go here
 		update_light()
 	if(rotation)
 		shuttleRotate(rotation)
+	if(proximity_monitor)
+		proximity_monitor.HandleMove()
 
 	update_parallax_contents()